1. Field of the Invention
The present invention relates generally to the field of wireless modems, and more particularly to a power inserter configuration for wireless modems.
2. Description of the Related Art
In order to provide high-speed Internet access, many cable companies are providing broadband Internet access via traditional coaxial cable. Modernly, cable systems comprise a fiber optic network, with coaxial cable lines connecting each residence to a “head-end.” These systems are commonly referred to as Hybrid Fiber Coax (HFC) systems. Even though cable access provides much greater performance than traditional telephone modem connections, the bandwidth is still not sufficient to provide high-speed access to a large number of users. In order to overcome this problem, wireless modems have recently been proposed in order to bypass the traditional coaxial cable, and connect directly to a “head-end” system.
As shown in FIG. 1, a wireless modem system for each residence may include an antenna connected to a transverter 6, which is usually mounted outside the residence near the antenna. In order to provide electrical power to the transverter 6, without supplying a separate electrical connection, power is “inserted” onto the coaxial data cable that connects the wireless modem 2 and the transverter 6. A power inserter block 4 may be implemented as shown by the circuit 16 of FIG. 2. A capacitor 12 blocks DC from the power inserter power source 10 from entering the modem. An inductor 14 blocks IF from the modem 2 from going to the power inserter power source 10. The result is that all of the IF energy and the DC power is sent to the transverter 6.
The addition of the power inserter circuit 4 saves the expense of installing a separate electrical power connection to the transverter 6, but adds two additional electrical connectors between the modem 2 and the transverter 6. Furthermore, the electrical connectors on the power inserter are generally the same type of connector. If a user accidentally connects the power inserter 4 in the reverse direction, the DC voltage will enter the modem's output connection and possibly cause permanent damage. Thus, there is a need to provide an improved power inserter configuration for wireless modems.